bump estree-walker to fix some svelte.walk bugs

Author: Conduitry

package-lock.json

@@ -61,7 +61,7 @@
     "c8": "^3.4.0",
     "codecov": "^3.0.0",
     "css-tree": "1.0.0-alpha22",
-    "estree-walker": "^0.6.0",
+    "estree-walker": "^0.6.1",
     "is-reference": "^1.1.1",
     "jsdom": "^12.2.0",
     "kleur": "^3.0.0",